Re: Ideas please

Tom Smith <TRCSmith@...>

With little information on the the whole subject I would suggest changing your spark plug leads. Altitude seems to be an issue, 5 thousand or above then change or test them.

Tom Smith  A&P/IA
Long-EZ N12TS

-----Original Message-----
From: Jim Jim.Rodrian@... [canard-aviators]
To: canard-aviators
Cc: COZY Builders Mailing List
Sent: Tue, Feb 12, 2019 4:53 pm
Subject: Re: [c-a] Ideas please

A friend had a somewhat similar experience with a Lycoming O-320 engine in his aircraft (RV-9A).  Originally, the “cough” occurred at altitude.  It eventually could be duplicated on the ground at a high power setting.  A compression check showed a problem with #4 cylinder.  The problem was a burnt intake valve (yes, intake valve.)

Jim Rodrian
Defiant N403R

On Feb 12, 2019, at 5:30 PM, Neil Clayton harvey4@... [canard-aviators] <canard-aviators@...> wrote:

Cozy Mark IV, IO-360, Lightspeed one side, Bendix on other side, fuel injection.

I have a persistent “glitch” that manifests itself as a “cough" at altitude and speed. Can’t seem to reproduce it on the ground.
It seems to be on the Lightspeed side because it doesn’t do it when running on just the Bendix.

Happens about every 15 minutes or so in flight.

I’ve been over all the wiring looking for bad grounds. I don’t think it’s the Lightspeed box itself (although I’m gonna try to replace the box).
I’ve replaced;
Plug wires
Ship’s battery
I’ve checked the installation is per Klaus’ instructions.
I’ve tried all mixture settings (rich/lean).

It’s not serious (the engine’s not gonna stop) but it sure gets my attention and I’m always on edge expecting the next event.
Anyone got any ideas?


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